On Wed, Dec 07, 2011 at 01:10:47AM +0000, Al Viro wrote:
> So let's add d_absolute_path(path, buf, buflen). Having it check that
> we'd walked to something mounted. And returning NULL otherwise. _Never_
Turns out that returning ERR_PTR(-EINVAL) is more convenient.
All right, here's a variant that does *NOT* return any vfsmount/dentry
pointers at all. And it does best-sane-effort wrt returning the pathname;
i.e. if it *is* something outside of chroot, that absolute pathname is
what we'll get.
diff --git a/fs/dcache.c b/fs/dcache.c
index 10ba92d..89509b5 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2439,16 +2439,14 @@ static int prepend_name(char **buffer, int *buflen, struct qstr *name)
/**
* prepend_path - Prepend path string to a buffer
* @path: the dentry/vfsmount to report
- * @root: root vfsmnt/dentry (may be modified by this function)
+ * @root: root vfsmnt/dentry
* @buffer: pointer to the end of the buffer
* @buflen: pointer to buffer length
*
* Caller holds the rename_lock.
- *
- * If path is not reachable from the supplied root, then the value of
- * root is changed (without modifying refcounts).
*/
-static int prepend_path(const struct path *path, struct path *root,
+static int prepend_path(const struct path *path,
+ const struct path *root,
char **buffer, int *buflen)
{
struct dentry *dentry = path->dentry;
@@ -2483,10 +2481,10 @@ static int prepend_path(const struct path *path, struct path *root,
dentry = parent;
}
-out:
if (!error && !slash)
error = prepend(buffer, buflen, "/", 1);
+out:
br_read_unlock(vfsmount_lock);
return error;
@@ -2500,15 +2498,17 @@ global_root:
WARN(1, "Root dentry has weird name <%.*s>\n",
(int) dentry->d_name.len, dentry->d_name.name);
}
- root->mnt = vfsmnt;
- root->dentry = dentry;
+ if (!slash)
+ error = prepend(buffer, buflen, "/", 1);
+ if (!error)
+ error = vfsmnt->mnt_ns ? 1 : 2;
goto out;
}
/**
* __d_path - return the path of a dentry
* @path: the dentry/vfsmount to report
- * @root: root vfsmnt/dentry (may be modified by this function)
+ * @root: root vfsmnt/dentry
* @buf: buffer to return value in
* @buflen: buffer length
*
@@ -2519,10 +2519,10 @@ global_root:
*
* "buflen" should be positive.
*
- * If path is not reachable from the supplied root, then the value of
- * root is changed (without modifying refcounts).
+ * If the path is not reachable from the supplied root, return %NULL.
*/
-char *__d_path(const struct path *path, struct path *root,
+char *__d_path(const struct path *path,
+ const struct path *root,
char *buf, int buflen)
{
char *res = buf + buflen;
@@ -2533,7 +2533,28 @@ char *__d_path(const struct path *path, struct path *root,
error = prepend_path(path, root, &res, &buflen);
write_sequnlock(&rename_lock);
- if (error)
+ if (error < 0)
+ return ERR_PTR(error);
+ if (error > 0)
+ return NULL;
+ return res;
+}
+
+char *d_absolute_path(const struct path *path,
+ char *buf, int buflen)
+{
+ struct path root = {};
+ char *res = buf + buflen;
+ int error;
+
+ prepend(&res, &buflen, "\0", 1);
+ write_seqlock(&rename_lock);
+ error = prepend_path(path, &root, &res, &buflen);
+ write_sequnlock(&rename_lock);
+
+ if (error > 1)
+ error = -EINVAL;
+ if (error < 0)
return ERR_PTR(error);
return res;
}
@@ -2541,8 +2562,9 @@ char *__d_path(const struct path *path, struct path *root,
/*
* same as __d_path but appends "(deleted)" for unlinked files.
*/
-static int path_with_deleted(const struct path *path, struct path *root,
- char **buf, int *buflen)
+static int path_with_deleted(const struct path *path,
+ const struct path *root,
+ char **buf, int *buflen)
{
prepend(buf, buflen, "\0", 1);
if (d_unlinked(path->dentry)) {
@@ -2579,7 +2601,6 @@ char *d_path(const struct path *path, char *buf, int buflen)
{
char *res = buf + buflen;
struct path root;
- struct path tmp;
int error;
/*
@@ -2594,9 +2615,8 @@ char *d_path(const struct path *path, char *buf, int buflen)
get_fs_root(current->fs, &root);
write_seqlock(&rename_lock);
- tmp = root;
- error = path_with_deleted(path, &tmp, &res, &buflen);
- if (error)
+ error = path_with_deleted(path, &root, &res, &buflen);
+ if (error < 0)
res = ERR_PTR(error);
write_sequnlock(&rename_lock);
path_put(&root);
@@ -2617,7 +2637,6 @@ char *d_path_with_unreachable(const struct path *path, char *buf, int buflen)
{
char *res = buf + buflen;
struct path root;
- struct path tmp;
int error;
if (path->dentry->d_op && path->dentry->d_op->d_dname)
@@ -2625,9 +2644,8 @@ char *d_path_with_unreachable(const struct path *path, char *buf, int buflen)
get_fs_root(current->fs, &root);
write_seqlock(&rename_lock);
- tmp = root;
- error = path_with_deleted(path, &tmp, &res, &buflen);
- if (!error && !path_equal(&tmp, &root))
+ error = path_with_deleted(path, &root, &res, &buflen);
+ if (error > 0)
error = prepend_unreachable(&res, &buflen);
write_sequnlock(&rename_lock);
path_put(&root);
@@ -2758,19 +2776,18 @@ SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size)
write_seqlock(&rename_lock);
if (!d_unlinked(pwd.dentry)) {
unsigned long len;
- struct path tmp = root;
char *cwd = page + PAGE_SIZE;
int buflen = PAGE_SIZE;
prepend(&cwd, &buflen, "\0", 1);
- error = prepend_path(&pwd, &tmp, &cwd, &buflen);
+ error = prepend_path(&pwd, &root, &cwd, &buflen);
write_sequnlock(&rename_lock);
- if (error)
+ if (error < 0)
goto out;
/* Unreachable from current root */
- if (!path_equal(&tmp, &root)) {
+ if (error > 0) {
error = prepend_unreachable(&cwd, &buflen);
if (error)
goto out;
diff --git a/fs/namespace.c b/fs/namespace.c
index 6d3a196..cfc6d44 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1048,15 +1048,12 @@ static int show_mountinfo(struct seq_file *m, void *v)
if (err)
goto out;
seq_putc(m, ' ');
- seq_path_root(m, &mnt_path, &root, " \t\n\\");
- if (root.mnt != p->root.mnt || root.dentry != p->root.dentry) {
- /*
- * Mountpoint is outside root, discard that one. Ugly,
- * but less so than trying to do that in iterator in a
- * race-free way (due to renames).
- */
- return SEQ_SKIP;
- }
+
+ /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
+ err = seq_path_root(m, &mnt_path, &root, " \t\n\\");
+ if (err)
+ goto out;
+
seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw");
show_mnt_opts(m, mnt);
@@ -2776,3 +2773,8 @@ void kern_unmount(struct vfsmount *mnt)
}
}
EXPORT_SYMBOL(kern_unmount);
+
+bool our_mnt(struct vfsmount *mnt)
+{
+ return check_mnt(mnt);
+}
diff --git a/fs/seq_file.c b/fs/seq_file.c
index 05d6b0e..dba43c3 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -449,8 +449,6 @@ EXPORT_SYMBOL(seq_path);
/*
* Same as seq_path, but relative to supplied root.
- *
- * root may be changed, see __d_path().
*/
int seq_path_root(struct seq_file *m, struct path *path, struct path *root,
char *esc)
@@ -463,6 +461,8 @@ int seq_path_root(struct seq_file *m, struct path *path, struct path *root,
char *p;
p = __d_path(path, root, buf, size);
+ if (!p)
+ return SEQ_SKIP;
res = PTR_ERR(p);
if (!IS_ERR(p)) {
char *end = mangle_path(buf, p, esc);
@@ -474,7 +474,7 @@ int seq_path_root(struct seq_file *m, struct path *path, struct path *root,
}
seq_commit(m, res);
- return res < 0 ? res : 0;
+ return res < 0 && res != -ENAMETOOLONG ? res : 0;
}
/*
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 4df9261..ed9f74f 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -339,7 +339,8 @@ extern int d_validate(struct dentry *, struct dentry *);
*/
extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...);
-extern char *__d_path(const struct path *path, struct path *root, char *, int);
+extern char *__d_path(const struct path *, const struct path *, char *, int);
+extern char *d_absolute_path(const struct path *, char *, int);
extern char *d_path(const struct path *, char *, int);
extern char *d_path_with_unreachable(const struct path *, char *, int);
extern char *dentry_path_raw(struct dentry *, char *, int);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index e313022..019dc55 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1942,6 +1942,7 @@ extern int fd_statfs(int, struct kstatfs *);
extern int statfs_by_dentry(struct dentry *, struct kstatfs *);
extern int freeze_super(struct super_block *super);
extern int thaw_super(struct super_block *super);
+extern bool our_mnt(struct vfsmount *mnt);
extern int current_umask(void);
diff --git a/security/apparmor/path.c b/security/apparmor/path.c
index 36cc0cc..b566eba 100644
--- a/security/apparmor/path.c
+++ b/security/apparmor/path.c
@@ -57,23 +57,44 @@ static int prepend(char **buffer, int buflen, const char *str, int namelen)
static int d_namespace_path(struct path *path, char *buf, int buflen,
char **name, int flags)
{
- struct path root, tmp;
char *res;
- int connected, error = 0;
+ int error = 0;
+ int connected = 1;
+
+ if (path->mnt->mnt_flags & MNT_INTERNAL) {
+ /* it's not mounted anywhere */
+ res = dentry_path(path->dentry, buf, buflen);
+ *name = res;
+ if (IS_ERR(res)) {
+ *name = buf;
+ return PTR_ERR(res);
+ }
+ if (path->dentry->d_sb->s_magic == PROC_SUPER_MAGIC &&
+ strncmp(*name, "/sys/", 5) == 0) {
+ /* TODO: convert over to using a per namespace
+ * control instead of hard coded /proc
+ */
+ return prepend(name, *name - buf, "/proc", 5);
+ }
+ return 0;
+ }
- /* Get the root we want to resolve too, released below */
+ /* resolve paths relative to chroot?*/
if (flags & PATH_CHROOT_REL) {
- /* resolve paths relative to chroot */
+ struct path root;
get_fs_root(current->fs, &root);
- } else {
- /* resolve paths relative to namespace */
- root.mnt = current->nsproxy->mnt_ns->root;
- root.dentry = root.mnt->mnt_root;
- path_get(&root);
+ res = __d_path(path, &root, buf, buflen);
+ if (res && !IS_ERR(res)) {
+ /* everything's fine */
+ *name = res;
+ path_put(&root);
+ goto ok;
+ }
+ path_put(&root);
+ connected = 0;
}
- tmp = root;
- res = __d_path(path, &tmp, buf, buflen);
+ res = d_absolute_path(path, buf, buflen);
*name = res;
/* handle error conditions - and still allow a partial path to
@@ -84,7 +105,10 @@ static int d_namespace_path(struct path *path, char *buf, int buflen,
*name = buf;
goto out;
}
+ if (!our_mnt(path->mnt))
+ connected = 0;
+ok:
/* Handle two cases:
* 1. A deleted dentry && profile is not allowing mediation of deleted
* 2. On some filesystems, newly allocated dentries appear to the
@@ -97,10 +121,7 @@ static int d_namespace_path(struct path *path, char *buf, int buflen,
goto out;
}
- /* Determine if the path is connected to the expected root */
- connected = tmp.dentry == root.dentry && tmp.mnt == root.mnt;
-
- /* If the path is not connected,
+ /* If the path is not connected to the expected root,
* check if it is a sysctl and handle specially else remove any
* leading / that __d_path may have returned.
* Unless
@@ -112,17 +133,9 @@ static int d_namespace_path(struct path *path, char *buf, int buflen,
* namespace root.
*/
if (!connected) {
- /* is the disconnect path a sysctl? */
- if (tmp.dentry->d_sb->s_magic == PROC_SUPER_MAGIC &&
- strncmp(*name, "/sys/", 5) == 0) {
- /* TODO: convert over to using a per namespace
- * control instead of hard coded /proc
- */
- error = prepend(name, *name - buf, "/proc", 5);
- } else if (!(flags & PATH_CONNECT_PATH) &&
+ if (!(flags & PATH_CONNECT_PATH) &&
!(((flags & CHROOT_NSCONNECT) == CHROOT_NSCONNECT) &&
- (tmp.mnt == current->nsproxy->mnt_ns->root &&
- tmp.dentry == tmp.mnt->mnt_root))) {
+ our_mnt(path->mnt))) {
/* disconnected path, don't return pathname starting
* with '/'
*/
@@ -133,8 +146,6 @@ static int d_namespace_path(struct path *path, char *buf, int buflen,
}
out:
- path_put(&root);
-
return error;
}
diff --git a/security/tomoyo/realpath.c b/security/tomoyo/realpath.c
index 738bbdf..36fa7c9 100644
--- a/security/tomoyo/realpath.c
+++ b/security/tomoyo/realpath.c
@@ -101,9 +101,8 @@ static char *tomoyo_get_absolute_path(struct path *path, char * const buffer,
{
char *pos = ERR_PTR(-ENOMEM);
if (buflen >= 256) {
- struct path ns_root = { };
/* go to whatever namespace root we are under */
- pos = __d_path(path, &ns_root, buffer, buflen - 1);
+ pos = d_absolute_path(path, buffer, buflen - 1);
if (!IS_ERR(pos) && *pos == '/' && pos[1]) {
struct inode *inode = path->dentry->d_inode;
if (inode && S_ISDIR(inode->i_mode)) {
--
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